This is a NIH Pathway to Independence Award (K99/R00 grant proposal, intended to promote the career of Dr. Marek Dudas, MD, PhD, a post-doctoral fellow at Childrens Hospital Los Angeles (CHLA), into an independent research position. The Candidate is a trained clinical embryologist with a significant track record of research in the field of craniofacial development and cleft palate, a major human birth defect. His goal is to secure a tenure-track faculty position and establish his own research program in the field of craniofacial malformations and fetal therapy. During the mentored, K99 phase of this award, the Candidate will attend advanced scientific workshops, career development sessions, and education in responsible conduct of research. He will work within a rich and collaborative environment of the Developmental Biology Program at CHLA, under the mentorship of the Program Director, Dr. David Warburton, DSc, MD, FRCP, FRCS, and co-mentors Drs. C. Shuler and V. Kaartinen. He will be trained in generation of a transgenic mouse strain with conditionally inactivated Trim33 gene, and use this strain to study the role of Trim33 in formation of the embryonic palate. During the independent, R00 phase of this award, the Candidate will elucidate the role of early TGF-P /BMP signaling in pathogenesis of cleft palate, and the principal mechanisms of palatal fusion. Epithelium of the first pharyngeal arch (PA1) is known to communicate with the underlying mesenchyme during processes of bone pre-patterning. This project will focus on early induction of facial skeletal structures dependent on signaling via TGF-P/BMP superfamily receptors ALK2 and ALK5 expressed in the PA1 ectoderm. We expect discovery of novel mechanisms leading to facial clefts (and possibly additional craniofacial malformations) by performing conditional deletion of ALK2 and ALK5 receptors specifically in the PA1 ectoderm. Moreover, genetic tools will be used for determination of the exact fate of the midline seam cells during palatal fusion, and experimental restoration of palatal fusion in TGF-03 knockouts suffering from cleft palate will be attempted as a prototypical experimental fetal therapy. This research is of major health relevance, because cleft palate in one of the most frequent malformations in humans, requiring costly treatment. [unreadable] [unreadable] [unreadable]